Soft faced hammer



June 20, 1961 A. DEL PESCO mu 2,989,102

SOFT FACED HAMMER Filed Feb. 5, 1959 l5. ATTORN YS This inventionrelates to a soft faced hammer, and particularly to the manner in whichthe percussion face material or insert is secured in its socket on thehammer head.

It is an object of the invention to provide securing means whichincludes a screw threaded stem projecting from the base of the insertand means for anchoring an end of said stem in the percussion facematerial so that the stem cannot pull out and so that relative rotationof the stem and insert is prevented.

A further object is to provide such means constituted in part by acommon and readily available type of bolt and in part by a cooperatingelement which is simple and inexpensive to make, to assemble with thebolt'and to mold into the percussion face material.

Another object is to provide certain improvements in the form,construction and arrangement to the several parts whereby the abovenamed and other objects may effectively be attained.

A practical embodiment of the invention is represented in theaccompanying drawings wherein:

FIG. 1 represents a side view of a hammer head, with part of the hammerhandle, having percussion faces of relatively soft material inserted inand secured to the sockets thereof, parts being shown in section alongthe median plane of the hammer head and parts being broken away;

FIG. 2 represents a top plan view of the special washer constitutingpart of the securing means, on an enlarged scale; a

FIG; 3 represents a side (or edge) view of the washer, as viewed fromthe right of FIG. 2;

FIG. 4 represents a bottom plan view of the washer;

FIG. 411 represents a detail plan view showing an alternative form ofwasher opening;

FIG. 5 represents a section, e.g., on the line V-V of FIG. 2, showingthe washer assembled on a bolt; and

FIG. 6 represents, on a smaller scale, a perspective view of the boltand washer embedded in the material of the percussion face, parts beingcut away.

Referring to-the' drawings, the hammer is shown as comprising a handle 1and a head 2 fixed thereon in any customary manner. The head of thistype of hammer is normally provided with two oppositely located sockets,one of which is shown at the left of FIG. 1 as having a flat bottomsurface 3 and a frusto-conical side surface 4 the top of whichintersects a flat annular surface 5. The hammer head is of metal' (e.g.,ferrous, or an aluminum or zinc alloy) and the maximum diameter of thesocket, in the plane of the surface 5, should be about A; to /5 of thediameter of the head in the same plane to ensure adequate strength inthe head around the zone of the socket. The taper of the socket may beabout 15 from the axis of the head. In the center of the surface 3 isdrilled a hole 6 of any suitable depth and threaded to receive the stemof the insert. A hammerhead as just described is conventional.

The percussion face insert, designated generally by the numeral 7,comprises a body of molded plastic material 8 shaped at its base 9 tofit snugly against the surfaces 3, 4 and 5 of the head, and an attachingmeans which is constituted by the bolt 10 and washer 11. The bolt atom10 is a carriage bolt" ofappropriate dimensions and materials having around head 12 and having the stem adjacent the head squared, as shown at13, the remainder of the stem 14being threaded to fit the hole or bore 6in the head.

The washer 11 is formed by stamping from a circular blank having afour-sided opening, the diagonals of which correspond approximately tothe diagonals of the squared stem 13 of the bolt, while the sides 15 ofthe opening are slightly inwardly bowed so that they will be deflectedand engage the bolt with an interference fit when the washer is mountedon the bolt (FIGS. 1 and 5) to prevent the washer from moving out of itsproper position during the pouring and molding of the plastic material.The washer is centrally dished, as indicated at 16, permitting the bolthead 12 to be as near the base of the insert as possible, and thusleaving the maximum amount of usable percussion face material betweenthe bolt head and the actual percussion face. Outwardly from the rim ofthe dished part of the washer it is divided into a plurality ofdownwardly slanting petals 17, here shown as being four, separated byradial cuts and having their ends 18 adjacent the cuts bent radiallyinwardly to lie in planes approximately parallel to the axis of the boltand passing through or near it. The deviation from parallelism may beconsiderable so long as the radially inwardly bent ends are more nearlyin such planes than in the plane of the washer perpendicular to the axisof the bolt.

An alternative form of washer, opening is shown in FIG. 4a, wherein theopening has straight sides with one or more filleted corners 19, thedimensions and tolerances being such that the corner edges of thesquared part 13 of the bolt will be forced to cut slightly into thefillets, thus providing an interference fit equivalent to that resultingfrom the inwardly bowed sides 15. The alternative form just describedshould be used particularly in cases where the maximum diameter of thebolt threads is such that it would exceed the minimum distances betweenopposite bowed sides 15; a washer with an opening so formed would tendto damage the threads when it is applied to the bolt, whereas theprovision of a square opening with filleted corners overcomes thisdifiiculty.

In the manufacture of the insert, the washer 11 is placed on the bolt10, as shown in FIG. 5, the bolt and washer assembly being placed in asuitably shaped mold. cavity with the threaded stem engaged in anopening thereof, and the cavity is filled with plastic material '(e.g.,nylon, polyvinyl chloride, rubber or other) in a fluid condition suchthat it may be caused to embed completely the washer and the head andsquared stem of.

. the bolt. The plastic material is then set andcured,

according to its nature.

The bolt head and washer are preferably located as near the base of theinsert as possible while still serving their purpose of holding theinsert securely, yet removably, in the socket of the hammer head. Thesoftness of the blow delivered duringus'e of such a hammer is a functionof the resiliency of the percussion face material and the depth of suchmaterial in the direction of the blow, hence it is desirable to have thebolt head as far as possible from the percussion face and also to use arelatively small headed bolt (e.g., the bolt head diameter should notsubstantially exceed one-half the maximum diameter of the insert, andmay be nearer one-third in larger inserts). The outwardly extendingpetals or quadrants of the washer substantially increase the effectivearea of the bolt-washer assembly to resist axial forces tending toseparate the plastic material from said assembly and the radiallyinwardly bent ends 18 firmly prevent relative rotation of the plasticmaterial and the washer which, in turn, cannot rotate around the boltbecause of the engagement of the bolts squared stem 13 with the washerssquared opening 15. As the insert is screwed into the socket thedownwardly inclined petals push downward and outward on the material inthe base of the insert forcing it strongly against the bottom and sidesof the socket. This force, coupled with the inherent resiliency of thepercussion face material, frictionally engaging the surfaces 3 and 4,prevents accidental loosening of the insert. Since the maximum exteriordiameter of the washer is less than the largest diameter of the socket,with the outer edges of the washer located near or below the level ofthe top of the socket 5, the downward and outward compressive forces arevery effectively concentrated in the part of the insert which lieswithin the socket.

While the bowed sides 15 (or fillets 19) of the washer opening grip thebolt stem firmly enough so that the washer is retained against the bolthead during manufacture, the washer is thereafter free to move with theadjacent plastic material in response to any shock waves caused byimpact of the percussion face on a work object during use, assuming thatthe impact is heavy enough to project a noticeable wave so deep into thepercussion face material. Thus substantially the entire mass of saidmaterial, from the actual percussion face to the bottom surfacesengaging the socket, is available for the resilient response to, anddissipation of, shock waves resulting from impact in use.

It will be understood that various changes may be made in the form,construction, arrangement and materials of the several parts withoutdeparting from the spirit and scope of the invention.

What we claim is:

l. A hammer head of the character described comprising, a body of rigidmaterial having a socket formed therein, means in said socket forengaging a part of an insert, and an insert of resilient material havingengaging means in the insert comprising an element having a stem and ahead, part of the stem being non-circular in cross-section, and a washerelement fitted on said noncircular part of the stem adjacent to saidhead and extending laterally beyond the periphery of said head, thewasher element and head and adjacent part of the stem being firmlyembedded in the resilient material of the insert with the said washerelement and head spaced both from the bottom surface of the insert andfrom the top surface thereof.

2. A hammer head according to claim 1 in which the socket isfrusto-conic in shape, in which the base of the insert comprises acomplementary frusto-conic extension and in which at least part of thewasher element lies within said extension.

3. A hammer head according to claim 1 in which the washer element isdished to form a recess accommodating the head and surrounded by aridge, in which the part of the washer radially outward of the ridge isdivided into downwardly slanted petal-shaped segments and in which partsof said segments are bent toward axial planes, whereby relative rotationof the washer element and resilient material is inhibited.

4. A hammer head of the character described comprising, a body of rigidmaterial having a tapering socket formed therein, a threaded holecentrally located in the bottom of said socket, and an insert ofresilient material having a tapering base portion adapted to fit in thesocket, the insert having a carriage bolt partially embedded in theresilient material with its threaded end projecting axially in aposition to be screwed into the hole in the socket, and the insert alsohaving a washer element fitted non-rotatably on the stem of the boltadjacent the head thereof, said washer element extending laterallybeyond the periphery of said head and said element and head being spacedboth from the bottom surface of the insert and from the top surfacethereof.

5. A hammer head according to claim 4 in which the washer element isdished to form a recess accommodating the head and surrounded by aridge, in which the part of the washer radially outward of the ridge isdivided into downwardly slanted petal-shaped segments and in which partsof said segments are bent toward axial planes, whereby relative rotationof the washer element and resilient material is inhibited.

6. A hammer head according to claim 5 in which the outer edges of thesegments are spaced from the bottom of the insert by a distance notsubstantially greater than the axial depth of the tapering base portion.

7. A hammer head according to claim 4 in which the washer is preventedby the bolt head from moving axially outward with respect to the boltand in which the washer is held only by frictional engagement with thebolt stem against forces tending to move it axially away from the bolthead.

8. A washer element adapted to fit on the squared stem part of acarriage bolt, the washer having a substantially square central hole atleast one side of which is inwardly bowed to provide an interference fitwith said squared stem part, the washer being centrally dished to forman upstanding annular wall having a diameter at its base at least asgreat as the diameter of the bolt head, the part of the washer radiallyoutward of said wall being divided into downwardly slanted petal-shapedsegments and parts of said segments being bent toward axial planes.

9. A washer element adapted to fit on the squared stem part of acarriage bolt, the Washer having a substantially square central hole atleast one corner of which is inwardly filleted to provide aninterference fit with an edge of said squared stem part, the washerbeing centrally dished to form an upstanding annular wall having adiameter at its base at least as great as the diameter of the bolt head,the part of the washer radially outward of said wall being divided intodownwardly slanted petal-shaped segments and parts of said segmentsbeing bent toward axial planes.

References Cited in the file of this patent UNITED STATES PATENTS2,596,780 Meyers et al. May 13, 1952 2,601,294 Jahn et a1 June 24, 1952FOREIGN PATENTS 721,679 Great Britain Jan. 12, 1955

